Dental intra-oral x-ray images are taken by using x-ray examination devices which typically include a multi-jointed arm construction and an x-ray source placed inside a housing. Typically, an elongated collimator limiting an x-ray beam has been attached or arranged to be attached to the housing. The imaging process includes placing the x-ray device in the proximity of the object area to be imaged and aiming the x-ray beam such that it will hit the sensor in a correct orientation and at a desired angle. Typically, one aims for arranging the beam perpendicular with respect to a film or some other detector of image information used in the imaging.
Problems related to aiming and orientating the beam as well and to the beam not being inclined or turned with respect to an image-data receiving means are generally known by dental professionals. Thus, different aiming arrangements have been developed to facilitate correct positioning of the x-ray source with respect to the sensor. One approach according to prior art is to attach the x-ray source and the image-data receiving means, such as a film, a phosphorous imaging plate, a CCD sensor or some other digital sensor, physically to each other for the duration of an exposure. Some prior-art systems and assemblies utilising this approach are presented in patent specifications U.S. Pat. No. 6,343,875 B1, U.S. Pat. No. 5,632,779 A, U.S. Pat. No. 4,507,798 A and U.S. Pat. No. 4,554,676 A.
However, many dental professionals find these systems, where the sensor placed within the patient's mouth should be physically connected to the x-ray device, difficult to use in practice. A reason for this is, first, that if all connections of the assembly are made before positioning the sensor in the mouth, it has proven difficult to aim the entire relatively heavy construction including the x-ray tube and its arm construction into a precisely correct position desired at a given instance. Secondly, if the sensor is first placed in the correct position in the mouth, it has proven difficult to e.g. attach an aiming shaft to assemble the construction such that the attaching process would not cause the sensor to move or cause discomfort to the patient.
In the field, one has also been contemplating arrangements in which information on the position of the imaging sensor would be obtained by means of sensors detecting the position, belonging to the imaging arrangement. Inter alia, a magnetic field has been disclosed to be utilised in positioning, but there have been no e.g. such arrangements based on measurement signals on the market which would be able to unambiguously determine the mutual spatial location and orientation of the imaging sensor and the radiation source, let alone to adjust and aim the beam accurately to the sensor based on such information. Again, evidently the only procedure on the market to adjust the size or shape of the beam generated by the intra-oral x-ray device that one could consider being based on technical arrangements of the apparatus itself has been manual replacement of collimator plates, collimator tubes or equivalent arranged into connection with the radiation source.